Cut the onion and bell pepper into medium-sized cubes, and cut the ravioli into strips.
Heat some oil in a pan and first fry the ravioli until golden. Add onions and peppers and then stir in the tomato sauce. Add a little water if necessary.
Season with salt and pepper, pluck the mozzarella into pieces and spread over the dumplings. Cover the pan with a lid to allow the mozzarella to melt, then serve.